Hot tube working



y 3 1942- J. w. KELso 2,289,289

HOT TUBE WORKING Filed June 10, 1939 JOHN M K 1.60,

Patented July 7, 1942 HOT TUBE WORKING John W. Kelso, East McKeesport, Pa., assignor to National Tube Company, a corporation of New Jersey Application June 10, 1939, Serial No. 278,563

4 Claims.

. This invention is particularly concerned with the working of hot metal tubes over a mandrel such as in the manner practiced in connection with the operation of a plug mill used in the production of seamless tubes.

According to the invention, salt is blown through the inside of a hot metal tube. Quickly following this, oil is injected into an end of the tube and is immediately followed by the injection of water into the same end.

The three materials are introduced to the inside of the tube after it has been heated to hot rolling temperature and just before it is passed over a mandrel. That is to say. the materials may be introduced just prior to the tube being passed through a plug mill.

The salt disassociates when it contacts the hot inside of the tube, this occurring with violence and blowing scale from the tube inside. The water also functions to blow the scale loose from the tube inside.

The most important function, however, of the water, is to float the oil ahead of the mandrel or plug as the tube is worked over the same by the mill. The oil performs the function of depositing carbon on the inside of the tube for the purpose of efiecting lubrication between this inside and the mandrel or plug, and if only oil is used, it tends to form heavy localized carbon deposits which sometimes scratch or tear the tube inside. This is prevented when the water is used, the water preventing the'oil forming 1ocalized heavy carbon deposits by carrying it ahead of the mandrel, the oil floating on top of the water and continuously depositing a smooth, thin layer of carbon which functions properly as a lubricant.

The amount of salt blown into the tube depends on the scale that has to be removed. Sufiicient oil must be used to prevent its being exhausted prior to the time the endof the tube is reached, while the water must be proportioned so that there is suflicient of the same to properly perform its function of floating the oil from end to end of the tube. Since the water is gradually converted to steam, this fact must be taken into consideration.

A specific example of the foregoing is illustrated by the accompanying drawing, in which:

Figure .1 15a sectional side view; and,

Figure 2 is an end view.

More specifically this drawing shows an in-.

clined skidway l down which tubes 2 roll on their way to the trough 3 which carries the tubes into the mill.

A releasable stop 4 serves to halt each tube as its end registers with an assembly consisting of three pipes 5 B and I which are interwelded to form a unit that can be slightly inserted or at least registered with the inside of the tube halted by the stop 4.

The pipe 5 connects with a salt hopper 8 containing ordinary table salt, the salt being blown through the pipe 5 by the action of an aspirator 9 provided with compressed air through a pipe "I, the pipe l9 being adjustable to permit regulation of the quantity of salt sucked up by the compressed air. The pipes 6 and 1, respectively, connect with oil and water supply lines H and I2. Suitable control valves are provided to control the introduction of the various materials into the tube ends.

Although not previously mentioned, another advantage connected with the use of the water vis that it aids in loosening scale spattered onto the inside of the pipe by the action of the molten salt.

The entire operation is completed in a few seconds just before dropping the pipe 2 into the trough 3. The tube then goes directly into the mill.

I claim:

1. A method of rolling ametal tube heated to hot rolling temperature over a mandrel, charac'terized by floating oil on water inside the tube ahead of the mandrel duringv the rolling so as to continuously deposit a smooth, thin layer of lubricating carbon on the tubes inside ahead of the mandrel.

2. A method of rolling a metal tube heated to hot rolling temperature over a mandrel, characterized'by floating oil on water inside the tube ahead of themandrel during the rolling so as to continuously deposit a smooth. thin layer of lubricating carbon on the tubes inside ahead of the mandrel, in conjunction with the introduction of salt to the tubes inside ahead of the water and oil.

3. A method of rolling a metal tube heated to hot rolling temperature over a mandrel, characterized by injecting oil and then water to float the oil, into the tubes inside immediately prior to its rolling and then rolling the tube 0\ er the mandrel, the oil floating on the water ahead of the mandrel during the rolling and continuously depositinga smooth, thin layer of lubricating carbon on the tubes inside.

4. A method of rolling a metal tube heated to hot rolling temperature over a mandrel, characterized by injecting oil and then water to float the oil, into the tubes inside immediately prior to its rolling and then rolling the tube over the mandrel, the oil floating on the water ahead of the mandrel during the rolling and continuously depositing a smooth, thin layer of lubricating carbon on the tubes inside, salt being introduced into the tubes inside immediately before the oil 

